Shutter device

ABSTRACT

When a second cam gear and a first cam gear rotate one turn, a shutter device changes to a first state, a second state, and a third state in this order. In the first state, the second cam gear charges a mirror lever drive spring and a blade drive spring, so that the first cam gear holds the blade lever. In the second state, the second cam gear releases charging of the mirror lever drive spring and charges the blade drive spring, so that the first cam gear releases holding of the blade lever. In the third state, the second cam gear releases charging of the mirror lever drive spring and charging of the blade drive spring, so that the first cam gear releases holding of the blade lever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a shutter device.

2. Description of the Related Art

In an imaging apparatus discussed in Japanese Patent ApplicationLaid-Open No. 2009-031513, a shutter cam gear which charges a shutterblade drive member and releases charging thereof is coupled with amirror cam gear which charges a mirror drive lever and releases chargingthereof.

In the imaging apparatus, the shutter cam gear and the mirror cam gearare driven in one direction, so that the imaging apparatus changes to astop phase, a live view phase, and an image capturing phase in thisorder.

Since the imaging apparatus discussed in Japanese Patent ApplicationLaid-Open No. 2009-031513 is configured to include a first curtain, theimaging apparatus is required to have both of the shutter cam gear whichcharges the shutter blade drive member and releases charging thereof andthe mirror cam gear which charges the mirror drive lever and releasescharging thereof.

In a case where reset scanning is performed on pixels of the imagesensor, i.e., an electronic first curtain, and after a predeterminedtime interval corresponding to a set shutter time in seconds, anexposure operation is performed in which a second curtain is caused torun, the first curtain is not involved in the exposure operation.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a shutter device foruse in an imaging apparatus including a mirror that can move back andforth in a photographic optical path, includes a shutter plate formedwith an aperture through which a photographic light flux passes, ashutter blade configured to close and open the aperture, a blade leverconfigured to rotate, thereby being coupled with the shutter blade, ablade return spring configured to urge the blade lever in a direction inwhich the shutter blade opens the aperture, a drive lever configured torotate around a rotation shaft of the blade lever to drive the bladelever, a blade drive spring configured to urge the drive lever, a mirrorlever configured to drive the mirror, a mirror lever drive springconfigured to urge the mirror lever, a charge cam member configured torotate to charge the mirror lever drive spring and the blade drivespring, the charge cam member having a first cam portion and a secondcam portion formed thereon, wherein the first cam portion comes intocontact with the mirror lever, and the second cam portion comes intocontact with the drive lever, a hold cam member configured to rotate toswitch between a state in which the blade lever is held so that theshutter blade closes the aperture and a state in which holding of theblade lever is released, wherein the hold cam member has a hold camportion formed thereon, the hold cam portion coming into contact withthe blade lever to hold the blade lever so that the shutter blade closesthe aperture, wherein the charge cam member and the hold cam member arearranged such that when the charge cam member rotates one turn, the holdcam member also rotates one turn, wherein when the charge cam member andthe hold cam member rotate one turn, the shutter device is arranged tochange to a first state, a second state, and a third state in thisorder, wherein in the first state, the charge cam member is arranged tocharge the mirror lever drive spring and the blade drive spring, so thatthe hold cam member holds the blade lever, wherein in the second state,the charge cam member is arranged to release charging of the mirrorlever drive spring and to charge the blade drive spring, so that thehold cam member releases holding of the blade lever, and wherein in thethird state, the charge cam member is arranged to release charging ofthe mirror lever drive spring and to release charging of the blade drivespring, so that the hold cam member releases holding of the blade lever.

According to an exemplary embodiment of the present invention, a shutterdevice can be provided. When a conventional first curtain is abolished,in an exemplary embodiment of the invention a conventional shutter camgear and a conventional mirror cam gear are made as a single componentin the shutter device, and the shutter device rotates the component oneturn, thus performing an operation needed to progress from animage-capturing standby state to an image-capturing completion state.

Further features and aspects of the present invention will becomeapparent from the following detailed description of exemplaryembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the invention.

FIGS. 1A and 1B are exploded perspective views illustrating a shutterunit.

FIGS. 2A and 2B are diagrams illustrating the shutter unit.

FIG. 3 is an exploded perspective view illustrating a first cam gear, asecond cam gear, a blade lever, a drive lever, a blade drive spring, anda ratchet.

FIGS. 4A to 4D are diagrams illustrating the drive lever, the bladelever, and the ratchet.

FIGS. 5A to 5C are diagrams illustrating the first cam gear and thesecond cam gear.

FIG. 6 is a timing chart illustrating operation timing of a mirrorlever, a main mirror, the blade lever, the drive lever, a coil, a bladegroup, an image sensor, and a cam gear control spring.

FIGS. 7A to 7C are diagrams illustrating a state of the shutter unit ina pre-release waiting state.

FIGS. 8A to 8C are diagrams illustrating a state of the shutter unit ina blade lever hold release state.

FIGS. 9A and 9B are diagrams illustrating a state of the shutter unit ina mirror up live view state;

FIGS. 10A to 10D are diagrams illustrating a state of the shutter unitin a set release state.

FIGS. 11A and 11B are diagrams illustrating a state of the shutter unitin a blade running state.

FIGS. 12A and 12B are diagrams illustrating a state of the shutter unitin a blade running completion state.

FIGS. 13A and 13B are diagrams illustrating a state of the shutter unitin a mirror lever charge and cam gear control spring charge releasestart state.

FIGS. 14A and 14B are diagrams illustrating a state of the shutter unitin a cam gear control spring charge release completion state.

FIGS. 15A and 15B are diagrams illustrating a state of the shutter unitin a mirror lever charge completion state.

FIGS. 16A and 16B are diagrams illustrating a state of the shutter unitin a blade lever holdable state.

FIGS. 17A and 17B are diagrams illustrating a state of the shutter unitin a drive lever charge state.

FIG. 18 is a timing chart illustrating operation timing of a mirrorlever, a main mirror, a blade lever, a drive lever, a coil, a bladegroup, an image sensor, and a cam gear control spring according to amodification.

FIGS. 19A and 19B are diagrams illustrating a state of the shutter unitin a mirror lever charge state.

FIGS. 20A and 20B are diagrams illustrating a state of the shutter unitin a mirror lever charge completion state.

FIGS. 21A and 21B are diagrams illustrating a state of the shutter unitin a blade lever holdable state.

FIGS. 22A and 22B are diagrams illustrating a state of the shutter unitin a drive lever charge and cam gear control spring charge release startstate.

FIGS. 23A and 23B are diagrams illustrating a state of the shutter unitin a cam gear control spring charge release completion state.

FIG. 24 is a central cross sectional view illustrating a digitalsingle-lens reflex camera body serving as an imaging apparatus accordingto an exemplary embodiment of the present invention and aninterchangeable lens.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

A shutter device and an imaging apparatus including the shutter deviceaccording to an exemplary embodiment of the present invention will behereinafter described with reference to FIGS. 1A and 1B to FIG. 24.

FIG. 24 is a central cross sectional view illustrating a digitalsingle-lens reflex camera body 101 serving as an imaging apparatusaccording to an exemplary embodiment of the present invention and aninterchangeable lens 201.

The interchangeable lens 201, which can be detachably attached to thecamera body 101, is fixed by a mount unit 102 provided on the camerabody 101 and a mount unit 202 provided on the interchangeable lens 201.When the interchangeable lens 201 is attached, a contact portion 103 ofthe camera body 101 is electrically connected to a contact portion 203of the interchangeable lens 201. Therefore, the camera body 101 detectsthat the interchangeable lens 201 is attached.

Further, power is supplied from the camera body 101 to theinterchangeable lens 201 via the contact portions 103 and 203, andcommunication for controlling the interchangeable lens 201 istransmitted via the contact portions 103 and 203. A light flux havingpassed through a focusing lens 204 of the interchangeable lens 201 isincident upon a main mirror 6 of the camera body 101. The main mirror 6is a mirror that can move back and forth in a photographic optical path.The main mirror 6 is a half mirror, and the light flux reflected by themain mirror 6 is guided to a viewfinder.

A light flux having passed through the main mirror 6 is reflecteddownward by a sub-mirror 105, and is guided to a focus detection unit106. The focus detection unit 106 detects the amount of defocus of thefocusing lens 204, and calculates the amount of lens drive for which thefocusing lens 204 is moved to attain a focused state of the focusinglens 204. Then, when the calculated amount of lens drive is transmittedto the interchangeable lens 201 via the contact portions 103 and 203,the interchangeable lens 201 controls a motor, not illustrated, therebymoving the focusing lens 204 and adjusting the focus.

The main mirror 6 is held in a main mirror holding frame 107, and themain mirror 6 is rotatably supported by a rotating shaft portion 6 b.The sub-mirror 105 is held by a sub-mirror holding frame 109. Thesub-mirror holding frame 109 is rotatably supported by a hinge shaft,not illustrated, with respect to the main mirror holding frame 107. Thelight flux guided to the viewfinder by the main mirror 6 forms an objectimage on a focusing screen 110. The imaging apparatus is configured suchthat a user can observe an object image on the focusing screen 110 via apentagonal prism 111 and an eyepiece lens 112.

A shutter unit 100 is provided behind the sub-mirror 105, and the bladegroup is closed in a normal state. An optical low-pass filter 114 isarranged behind the shutter unit 100. Behind the optical low-pass filter114, an image sensor 116 and a cover member 117 are provided. The imagesensor 116 is held by an image sensor holder 115 fixed to the housingwith screws, not illustrated. The cover member 117 protects the imagesensor 116. A rubber member 118 holds the optical low-pass filter 114and seals a portion between the optical low-pass filter 114 and theimage sensor 116. The imaging apparatus is configured such that during ashooting operation, the light flux having passed through the opticallow-pass filter 114 is incident upon the image sensor 116.

FIG. 1A is an exploded perspective view illustrating the shutter unit100 as viewed from a front thereof. FIG. 1B is an exploded perspectiveview illustrating the shutter unit 100 as viewed from a back thereof.

As illustrated in FIG. 1A, an aperture 1 a is formed in a centralportion of the shutter base plate (shutter plate) 1. An optical axis 49passes through the center of the aperture 1 a. A shaft 1 b, a shaft 1 c,and a shaft 1 d, which are parallel to the optical axis 49, are formedon the shutter base plate 1. A drive lever 11 and a ratchet 16 arerotatably supported by the shaft 1 b. A blade lever 15 is supported bythe drive lever 11, and rotates around the shaft 1 b, which is therotational axis of the drive lever 11. A first cam gear 21 is rotatablysupported by the shaft 1 c. A second cam gear 22 is rotatably supportedby the shaft 1 d. The shaft 1 b functions as a first shaft, the shaft 1c functions as a third shaft, and the shaft 1 d functions as a secondshaft.

The shaft 1 b, the shaft 1 c, and the shaft 1 d are formed to be inparallel to the optical axis 49. Accordingly, the shaft 1 c and theshaft 1 d are parallel to the shaft 1 b. The first cam gear 21 functionsas a hold cam member, and the second cam gear 22 functions as a chargecam member.

Drive force provided by a motor 47 having an output shaft parallel tothe optical axis 49 is transmitted to the second cam gear 22 via aplurality of reduction gear trains 48 having rotational shafts parallelto the optical axis 49.

A first cam 22 a, which comes into contact with a cam follower 36 a of amirror drive lever 36, described below, is provided on the second camgear 22. A second cam 22 c, which comes into contact with a roller 13provided on the drive lever 11, is formed on the second cam gear 22. Thesecond cam 22 c functions as a charge cam portion. The first cam 22 aand the second cam 22 c are formed at different portions in a directionof the shaft 1 d of the second cam gear 22 (third shaft direction). Thesecond cam 22 c is located closer to the shutter base plate 1 than thefirst cam 22 a.

Further, a third cam 22 d, which comes into contact with a cam gearcontrol spring 50 for controlling rotation of the second cam gear 22, isformed on the second cam gear 22. The third cam 22 d is located closerto the shutter base plate 1 than the second cam 22 c. In other words,the cam gear control spring 50 functions a rotation control spring forsuppressing rotation of the second cam gear 22 according to therotational position of the second cam gear 22. The third cam 22 d, whichfunctions as a third cam portion, and is located closer to the shutterbase plate 1 than the second cam 22 c, which functions as the second camportion.

The drive lever 11 and the ratchet 16 are pivottaly supported by theshaft 1 b, the first cam gear 21 is pivottaly supported by the shaft 1c, and the second cam gear 22 is pivottaly supported by the shaft 1 d,whereby an auxiliary base plate (auxiliary plate) 31 is fixed to theshutter base plate 1. The blade lever 15 is pivottaly supported by thedrive lever 11, and rotates around the shaft 1 b like the drive lever11. In the auxiliary base plate 31, shaft receiving holes are formed.The shaft 1 b, the shaft 1 c, and the shaft 1 d are respectivelyinserted into the shaft receiving holes. The drive lever 11, the bladelever 15, the ratchet 16, the first cam gear 21, and the second cam gear22 are sandwiched between the shutter base plate 1 and the auxiliarybase plate 31.

A shaft 31 a is formed on the auxiliary base plate 31. The mirror lever36 is rotatably supported by the shaft 31 a. The shaft 31 a is alsoformed parallel to the optical axis 49. Accordingly, the shaft 31 a isparallel to the shaft 1 b.

After the mirror drive lever 36 is installed to be pivottaly supportedby the shaft 31 a, a screw 37 is screwed into an end of the shaft 31 aof the auxiliary base plate 31. The screw 37 fixes the mirror drivelever 36 to the shaft 31 a in such a manner that the mirror drive lever36 can rotate with respect to the shaft 31 a.

The cam follower 36 a is provided on the mirror lever 36, and comes intocontact with the first cam 22 a of the second cam gear 22. A contactportion 36 b is formed on the mirror lever 36, and comes into contactwith a shaft portion 6 a of the main mirror 6. A mirror lever drivespring 39 is put on the mirror lever 36. The mirror lever drive spring39 urges the mirror lever 36 in a clockwise direction in FIG. 1A, i.e.,a direction in which the main mirror 6 is raised.

The main mirror 6 reciprocally rotates around the rotating shaft portion6 b. As a result, the main mirror 6 can be at a lower position where themain mirror 6 is held at an angle of 45 degrees with respect to theoptical axis 49 to guide a photographic light flux to the pentagonalprism 111 and an upper position where the main mirror 6 is retracted outof the photographic light flux to guide the photographic light flux tothe image sensor 116.

Further, a mirror drive spring 7 is attached to the mirror drive lever36. An end portion of the mirror drive spring 7 is put on the shaftportion 6 a of the main mirror 6. Accordingly, the main mirror drivespring 7 urges the main mirror 6 downward.

Ratchet teeth 16 a are formed on the ratchet 16. An engaging clawportion 31 b serving as an engaging member that engages the ratchetteeth 16 a is formed on the auxiliary base plate 31.

A photo-sensor 32 for detecting the rotational position of the bladelever 15 is attached to the auxiliary base plate 31

As illustrated in FIG. 1B, a yoke 33 and a coil 34 are fixed to theauxiliary base plate 31 by a screw 35. When a voltage is applied to thecoil 34, magnetic force is generated in the yoke 33.

As illustrated in FIG. 1A, a first fixed portion 38 a and a second fixedportion 38 b are formed on a flexible wiring board 38. The first fixedportion 38 a is fixed to the auxiliary base plate 31. The second fixedportion 38 b is fixed to the shutter base plate 1. The flexible wiringboard 38 is connected to the coil 34 and the photo-sensor 32 with thefirst fixed portion 38 a. A phase pattern portion 38 c for detecting aphase of a phase contact piece 23 attached to the first cam gear 21 isformed on the second fixed portion 38 b of the flexible wiring board 38.

A semilunar cushioning member 3 made of an elastic member such as rubberis fixed to an upper portion of an arc-shaped hole 1 e of the shutterbase plate 1.

As illustrated in FIG. 1B, a cover plate 2 is fixed to a back surfaceside of the shutter base plate 1. An aperture 2 a is formed in a centralportion of the cover plate 2. The aperture 2 a is formed atsubstantially the same position as the aperture 1 a of the shutter baseplate 1. The apertures 1 a and 2 a limit a light flux passing throughthe shutter unit 100.

A blade chamber for accommodating the blade group is formed between theshutter base plate 1 and the cover plate 2. The blade group includes afirst blade 41, a second blade 42, a main arm 43, and a sub-arm 44.

The first blade 41 and the second blade 42 serving as the shutter bladeare made of polyethylene terephthalate including blackening. The firstblade 41 is rotatably supported by the main arm 43 and the sub-arm 44with pins 45. The second blade 42 is rotatably supported by the main arm43 and the sub-arm 44 with the pins 45.

The main arm 43 is rotatably supported by a shaft 1 f formed on theshutter base plate 1. The sub-arm 44 is rotatably supported by a shaft 1g formed on the shutter base plate 1. The main arm 43 rotates around theshaft 1 f, and the sub-arm 44 rotates around the shaft 1 g, so that thefirst blade 41 and the second blade 42 perform parallel link motion.

A hole 43 a for engaging with an engaging portion 15 a of the bladelever 15, described below, is formed in the main arm 43. The blade lever15 functions as a blade lever that couples with the first blade 41 andthe second blade 42. A blade return spring 46 is put on the sub-arm 44.The blade return spring 46 urges the sub-arm 44 in the clockwisedirection in FIG. 1B. That is, the urging force applied by the bladereturn spring 46 causes the first blade 41 and the second blade 42 torun in a direction to open the apertures 1 a and 2 a.

When the first blade 41 and the second blade 42 finish running in thedirection to open the apertures 1 a and 2 a with the urging forceapplied by the blade return spring 46, the first blade 41 and the secondblade 42 collide with a blade cushioning member 4. The blade cushioningmember 4 is fixed to a rectangular shaft portion 1 h arranged on theshutter base plate 1. The blade cushioning member 4 has a rectangularexternal shape. The shaft portion 1 h is also formed in the samerectangular shape as the external shape of the blade cushioning member4. A side of the external shape of the blade cushioning member 4 isformed to be substantially parallel to a side of the shaft portion 1 hwhile the blade cushioning member 4 is attached to the shutter baseplate 1. In the present exemplary embodiment, the blade cushioningmember 4 and the shaft portion 1 h are in the rectangular shapes, butthe same actions and effects can be achieved as long as they are inpolygonal shapes that satisfy the above conditions.

The blade cushioning member 4 is made of a material absorbing shock,e.g., rubber material such as chloroprene rubber, butyl rubber,polyurethane rubber, and silicone rubber, or elastomer. A periphery ofthe blade cushioning member 4 is covered with a blade contact member 5.The blade contact member 5 is made of a material having higher degree ofresistance to abrasion than the blade cushioning member 4, such as metaland plastic. The blade contact member 5 is fixed to the blade cushioningmember 4. When the first blade 41 and the second blade 42 collide withthe blade cushioning member 4, the first blade 41 and the second blade42 are configured not to be in direct contact with the blade cushioningmember 4. In this configuration, when the first blade 41 and the secondblade 42 collide with the blade cushioning member 4, the bladecushioning member 4 is prevented from abrasion.

FIG. 2A is a diagram illustrating the shutter unit 100 as viewed from afront thereof. FIG. 2B is a diagram illustrating the shutter unit 100 asviewed from a side thereof.

As illustrated in the figures, the shaft 1 c serving as the center ofrotation of the first cam gear 21 provided on the shutter base plate 1is formed at a position opposite to the optical axis 49 with respect toa line connecting between the shaft 1 b serving as the center ofrotation of the drive lever 11 and the blade lever 15 and the shaft 1 dserving as the center of rotation of the second cam gear 22. The shaft 1b, the shaft 1 c, and the shaft 1 d are formed such that a triangleformed by connecting the shaft 1 b, the shaft 1 c, and the shaft 1 d(indicated by a broken line) becomes an acute-angled triangle. This canreduce the size of the shutter drive unit.

As illustrated in FIG. 2B, the contact portion 36 b of the mirror lever36 is located at an upper side in the figure with respect to the opticalaxis 49. The drive lever 11 is located at a lower side in the figurewith respect to the optical axis 49. As illustrated in FIG. 2B, thecontact portion 36 b of the mirror lever 36 and the drive lever 11 arelocated substantially at the same position in the direction of theoptical axis 49. In other words, the contact portion 36 b of the mirrorlever 36 can be arranged in the space higher than the optical axis 49,and the drive lever 11 can be arranged in the space lower than theoptical axis 49. In this configuration, the size of the shutter driveunit can be reduced in the direction of the optical axis 49.

FIG. 3 is an exploded perspective view illustrating the first cam gear21, the second cam gear 22, the blade lever 15, the drive lever 11, ablade drive spring 14, and the ratchet 16. An armature holding portion11 a, a penetrating hole 11 b, a protrusion 11 c, a roller hold shaft 11d, a protruding portion 11 e, and a cylindrical portion 11 f are formedon the drive lever 11.

An armature 12 is attached to the armature holding portion 11 a. Theroller 13 is held by the roller hold shaft 11 d.

The engaging portion 15 a, a protruding portion 15 b, a light-shieldingwall portion 15 c, a roller receiving portion 15 d, a cam follower 15 e,and an inclined portion 15 f are formed on the blade lever 15.

A gear 21 a and a cam 21 b are formed on the first cam gear 21. Thefirst cam 22 a, a gear 22 b, the second cam 22 c, and a third cam 22 dare formed on the second cam gear 22.

FIGS. 4A to 4D are diagrams illustrating the drive lever 11, the bladelever 15, and the ratchet 16. FIGS. 4A and 4C are diagrams illustratingthe drive lever 11, the blade lever 15, and the ratchet 16 as viewedfrom the shutter base plate 1.

FIG. 4B is a cross sectional view taken along line A-A in FIG. 4A, whichis a cross sectional view illustrating the armature holding portion 11 aof the drive lever 11. FIG. 4D is a cross sectional view taken alongline B-B in FIG. 4C, which is a diagram illustrating a relationshipbetween the roller hold shaft 11 d of the drive lever 11 and the rollerreceiving portion 15 d of the blade lever 15.

As illustrated in FIGS. 4A and 4C, the protruding portion 11 e is formedon the drive lever 11, and the protruding portion 15 b is formed on theblade lever 15. In the state as illustrated in FIG. 4A, the protrudingportion 11 e is in contact with the protruding portion 15 b. In thestate as illustrated in FIG. 4C, the protruding portion 11 e is not incontact with the protruding portion 15 b.

As illustrated in FIG. 4B, the armature holding portion 11 a is formedon the drive lever 11. The penetrating hole 11 b is formed in thearmature holding portion 11 a. A flange 12 b is provided at an end of anarmature shaft 12 a. The external diameter of the flange 12 b is largerthan the internal diameter of the penetrating hole 11 b. The other endof the armature shaft 12 a is loosely inserted into the penetrating hole11 b. After the armature 12 is attached to the armature shaft 12 a, theother end of the armature shaft 12 a is crimped.

An armature spring 17, i.e., a compression spring, is arranged aroundthe armature shaft 12 a between the armature 12 and the armature holdingportion 11 a. The armature spring 17 applies urging force in a directionto move the armature 12 away from the armature holding portion 11 a.

The hemispheric protrusion 11 c is formed at a position facing theflange 12 b of the armature holding portion 11 a.

As illustrated in FIGS. 4A, 4C, and 4D, the roller 13 is rotatably heldin the roller hold shaft 11 d of the drive lever 11. Lubricating oil isapplied between the roller hold shaft 11 d and the roller 13. The roller13 is in contact with a second cam surface 22 c of the second cam gear22.

The protruding portion 11 e is formed on the drive lever 11. Theprotruding portion 11 e is in contact with the protruding portion 15 bof the blade lever 15.

The protruding engaging portion 15 a is formed on the blade lever 15.The engaging portion 15 a penetrates the arc-shaped hole 1 e of theshutter base plate 1, and engages with the hole 43 a of the main arm 43at the back surface side of the shutter base plate 1. Accordingly, themain arm 43 rotates in synchronization with the blade lever 15. The camfollower 15 e is formed on the blade lever 15. The cam follower 15 ecomes into contact with a cam surface 21 b of the first cam gear 21. Twolight-shielding wall portions 15 c are provided on the blade lever 15.When the light-shielding wall portion 15 c shields light received by thephoto-sensor 32, the photo-sensor 32 detects the rotational position ofthe blade lever 15. In other words, the photo-sensor 32 functions as adetecting unit, and the light-shielding wall portion 15 c functions as aportion to be detected.

The roller receiving portion 15 d is formed on the blade lever 15. Theroller receiving portion 15 d extends towards the roller hold shaft 11d, so that the roller 13 held on the roller hold shaft 11 d does notdrop.

The roller receiving portion 15 d is formed in a range in which theroller hold shaft 11 d moves when the blade lever 15 is driven by theurging force of the blade return spring 46 in a direction in which thefirst blade 41 and the second blade 42 open the apertures 1 a and 2 a.

Thus, no matter how the drive lever 11 and the blade lever 15 arearranged, the roller receiving portion 15 d faces the roller hold shaft11 d. Therefore, even when the lubricating oil applied to the portionbetween the roller hold shaft 11 d and the roller 13 exudes, thelubricating oil attaches to the roller receiving portion 15 d, but thelubricating oil does not exude to the shutter base plate 1.

As illustrated in FIG. 4D, the cylindrical portion 11 f of the drivelever 11 engages with the shaft 1 b of the shutter base plate 1, so thatthe drive lever 11 is rotatably supported by the shaft 1 b of theshutter base plate 1. Then, the blade lever 15 is engaged with thecylindrical portion 11 f of the drive lever 11, so that the blade lever15 is rotatably supported by the cylindrical portion 11 f of the drivelever 11. Therefore, the blade lever 15 rotates with respect to theshutter base plate 1, and the drive lever 11 rotates with respect to theshutter base plate 1 around the same axis as that of the blade lever 15.

As illustrated in FIG. 4D, the blade drive spring 14, i.e., a torsionspring, is provided between the ratchet 16 and the drive lever 11. Oneend 14 a of the blade drive spring 14 is fixed to the drive lever 11,and the other end 14 b of the blade drive spring 14 is fixed to theratchet 16. The blade drive spring 14 urges the drive lever 11 in thecounterclockwise direction in FIG. 4A. The free length of the bladedrive spring 14 is set longer than the interval between the drive lever11 and the ratchet 16, and the blade drive spring 14 serves as thecompression spring, thereby urging the drive lever 11 to the shutterbase plate 1.

As illustrated in FIG. 4D, the inclined portion 15 f is formed on theblade lever 15. Since the inclined portion 15 f is formed, the rollerreceiving portion 15 d of the blade lever 15 extends from the center ofrotation of the blade lever 15 in a substantially cone shape. If theroller receiving portion 15 d extends from the center of rotation of theblade lever 15 in a substantially cylindrical shape, inertial forceacting on the blade lever 15 increases when the blade lever 15 rotates.In the present exemplary embodiment, the roller receiving portion 15 dis formed in the substantially cone shape, so that the roller receivingportion 15 d can be formed while suppressing an increase in the inertialforce of the blade lever 15.

A procedure for fixing the drive lever 11 to the blade lever 15 will bedescribed. First, the roller 13 is inserted into the roller hold shaft11 d. Thereafter, the blade lever 15 is inserted into the cylindricalportion 11 f in the state as illustrated in FIG. 4A. Then, when theblade lever 15 is rotated in the counterclockwise direction with respectto the drive lever 11, the state as illustrated in FIG. 4C is attained.In the state as illustrated in FIG. 4C, the roller hold shaft 11 d islocated between the roller receiving portion 15 d and thelight-shielding wall portion 15 c, and therefore, the drive lever 11does not come off from the blade lever 15. The range in which the rollerhold shaft 11 d moves in the axial direction between the rollerreceiving portion 15 d and the light-shielding wall portion 15 c issmaller than the thickness of the roller 13. Therefore, the roller 13does not come off from the roller hold shaft 11 d.

In this manner, the drive lever 11, the roller 13, and the blade lever15 are integrated, and the cylindrical portion 11 f of the drive lever11 is engaged with the shaft 1 b of the shutter base plate 1.

FIGS. 5A to 5C are diagrams illustrating the first cam gear 21 and thesecond cam gear 22. The gear 21 a of the first cam gear 21 is in meshwith the gear 22 b of the second cam gear 22, whereby rotation istransmitted. The gear 21 a functions as a first gear unit, and the gear22 b functions as a second gear unit. The cam 21 b is a hold cam portiontraced by the cam follower 15 e of the blade lever 15.

In the state as illustrated in FIG. 5A, the cam follower 15 e is incontact with the cam 21 b. In this state, counterclockwise force isexerted on the blade lever 15 by the blade return spring 46, but sincethe cam 21 b and the cam follower 15 e are in contact with each other,the blade lever 15 does not rotate. Therefore, the first cam gear 21holds the blade lever 15 such that the first blade 41 and the secondblade 42 close the apertures 1 a and 2 a. In other words, the cam 21 bfunctions as a hold cam portion.

The state as illustrated in FIG. 5B is attained when the first cam gear21 rotates in the counterclockwise direction from the state asillustrated in FIG. 5A. FIG. 5C is a diagram illustrating the state asillustrated in FIG. 5B as viewed from the shutter base plate. In thestate as illustrated in FIG. 5B, the contact between the cam 21 b andthe cam follower 15 e is released, and the blade lever 15 rotates in thecounterclockwise direction by the blade return spring 46.

When the first cam gear 21 rotates in the counterclockwise directionfrom the state as illustrated in FIGS. 5B and 5C, the cam 21 b comesinto contact with the cam follower 15 e, which causes the blade lever 15to rotate in the clockwise direction. As a result, the blade returnspring 46 is charged (has a load force applied to it).

The phase contact piece 23 is arranged on the bottom surface of the camportion 21 b. The phase contact piece 23 comes into contact with thepattern portion 38 c of the flexible wiring board (FPC) 38, and detectsthe phase of rotation of the first cam gear 21.

The gear 22 b of the second cam gear 22 is in mesh with the reductiongear train 48, and transmits the drive force of the motor 47.

The number of teeth of the gear 22 b and the number of teeth of the gear21 a are set at the same number. The gear 22 b and the gear 21 a are inmesh with each other with a predetermined phase. Accordingly, when thefirst cam gear 21 rotates one turn, the second cam gear 22 also rotatesone turn, and the first cam gear 21 and the second cam gear 22 rotatewith the predetermined phase and at the same number of rotations.

The first cam 22 a serving as the first cam portion is in contact withthe cam follower 36 a of the mirror lever 36, and causes the mirrorlever 36 to rotate to the upper position and the lower position. Morespecifically, when the second cam gear 22 is at a first position wherethe first cam 22 a and the cam follower 36 a of the mirror lever 36 arein contact with each other, the second cam gear 22 causes the mainmirror 6 to move downward to cause the main mirror 6 to enter into thephotographic optical path. When the second cam gear 22 is at a secondposition where the first cam 22 a and the cam follower 36 a of themirror lever 36 are no longer in contact with each other, the second camgear 22 causes the main mirror 6 to move upward to retract the mainmirror 6 out of the photographic optical path.

The second cam 22 c serving as the second cam portion comes into contactwith the roller 13 held on the drive lever 11, and performs charge andrelease operation of the drive lever 11.

The third cam 22 d comes into contact with a movable arm portion 50 a ofthe cam gear control spring 50 provided on the shutter base plate 1.With the rotation of the second cam gear 22, the cam gear control spring50 attains either a charged state or a charge-released state. Thiscontrols the rotation of the second cam gear 22. As illustrated in FIGS.5B and 5C, when the cam gear control spring 50 is charged, the rotationof the second cam gear 22 is suppressed by causing the cam gear controlspring 50 to give a side pressure to the third cam 22 d. Morespecifically, the cam gear control spring 50 brakes the second cam gear22 from when the cam gear control spring 50 starts charging operation towhen the cam gear control spring 50 finishes charging operation. On theother hand, the cam gear control spring 50 pushes the second cam gear 22to support rotation from when the cam gear control spring 50 startscharging release operation to when the cam gear control spring 50finishes charging release operation.

The third cam 22 d is located closer to the shutter base plate than thesecond cam 22 c. As a result, the third cam 22 d coming into contactwith the cam gear control spring 50 can be easily formed. Moreover, thethird cam 22 d does not result in increasing the size of the drive unitof the shutter.

FIG. 6 is a timing chart illustrating operation timing of the mirrorlever 36, the main mirror 6, the blade lever 15, the drive lever 11, thecoil 34, the blade group, the image sensor 116, and the cam gear controlspring 50. The operation of the shutter unit 100 will be described withreference to FIGS. 7A to 7C to FIGS. 17A and 17B when the shutter unit100 changes from a state A as illustrated in FIG. 6 to a state N.

The state A as illustrated in FIG. 6 is a pre-release waiting state.FIGS. 7A to 7C illustrate the state of the shutter unit 100 in thepre-release waiting state. FIG. 7A is a diagram illustrating the shutterunit 100 as viewed from the main mirror 6. FIG. 7B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

In the pre-release waiting state, the first cam gear 21 and the secondcam gear 22 stop at positions as illustrated in FIGS. 7A and 7B.

The roller 13 held on the drive lever 11 is in contact with a cam topportion 22 d of the second cam 22 c of the second cam gear 22. The drivelever 11 is in a state where the blade drive spring 14 is overcharged.The state where the blade drive spring 14 is overcharged means a statein which the coil 34 is energized, whereby the yoke 33 moves beyond theposition where the armature 12 can be held, and the drive lever 11 ismoved in a direction in which the blade drive spring 14 is charged. Asillustrated in FIG. 7C, in the over-charged state, the armature 12 is incontact with the yoke 33, but the armature holding portion 11 a of thedrive lever 11 compresses the armature spring 17, and the flange unit 12b of the armature 12 and the protrusion unit 11 c of the blade drivemember move away from each other.

The cam follower 15 e of the blade lever 15 is in contact with the camtop 21 c of the cam 21 b of the first cam gear 21. As a result, theblade lever 15 is maintained in a state as illustrated in the figure.

In FIG. 7B, the blade return spring 46 urges the sub-arm 44 in theclockwise direction, but the blade lever 15 is held. Accordingly,against the urging force of the blade return spring 46, the first blade41 and the second blade 42 are held in a state in which the apertures 1a and 2 a are closed.

At this occasion, the roller receiving portion 15 d of the blade lever15 is at the position facing the roller 13, so that this prevents theroller 13 from coming off from the roller hold shaft 11 d.

The cam follower 36 a of the mirror lever 36 comes into contact with acam top portion 22 e of the first cam 22 a of the second cam gear 22,whereby the mirror lever 36 maintains the mirror lever drive spring 39in the charged state as illustrated in FIG. 7A.

The main mirror 6 is urged by the main mirror drive spring 7 in adownward direction. The main mirror 6 comes into contact with a stopper,not illustrated, and the main mirror 6 is at the lower position. At thisoccasion, there is a clearance between the shaft portion 6 a of the mainmirror 6 and the contact portion 36 b of the mirror lever 36. Therefore,even if error occurs in the position of the mirror lever 36, theposition of the main mirror 6 is positioned at the correct position bythe stopper, not illustrated.

At this occasion, the arm portion 50 a of the cam gear control spring 50is in contact with the third cam 22 d of the second cam gear 22, and thecharging operation of the cam gear control spring 50 is completed.

When a release signal is input in the pre-release waiting state, thecoil 34 is energized, and the yoke 33 attracts the armature 12. At thesame time, the motor 47 is energized, and the first cam gear 21 and thesecond cam gear 22 rotate, so that a blade lever hold release state B asillustrated in FIG. 6 is attained.

The state B as illustrated in FIG. 6 is the blade lever hold releasestate. FIGS. 8A to 8C illustrate a state of the shutter unit 100 in theblade lever hold release state. FIG. 8A is a diagram illustrating theshutter unit 100 as viewed from the main mirror 6. FIG. 8B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

In the blade lever hold release state, the first cam gear 21 and thesecond cam gear 22 stop at positions as illustrated in FIGS. 8A and 8B.

In this explanation, only the difference from the pre-release waitingstate as illustrated in FIGS. 7A to 7C will be described, anddescription about the elements that have not changed from thepre-release waiting state is omitted.

When the motor 47 is energized, the first cam gear 21 rotates from thestate as illustrated in FIGS. 7A to 7C to the state as illustrated inFIGS. 8A to 8C. When the first cam gear 21 attains the state asillustrated in FIGS. 8A to 8C, the cam follower 15 e of the blade lever15 is no longer in contact with the cam top 21 c of the cam 21 b of thefirst cam gear 21. More specifically, the cam 21 b moves out of thetrack along which the cam follower 15 e of the blade lever 15 rotates,and the held blade lever 15 is released, so that the blade lever 15becomes rotatable with respect to the shaft 1 b.

When holding of the held blade lever 15 is released, the first blade 41and the second blade 42 run in a direction to open the apertures 1 a and2 a with the urging force of the blade return spring 46, which urges thesub-arm 44. Accordingly, the blade lever 15 rotates with respect to theshaft 1 b.

At this occasion, the roller 13 attached to the roller hold shaft 11 dof the drive lever 11 moves along the roller receiving portion 15 d ofthe blade lever 15 not to detach from the roller hold shaft 11 d.

In the blade lever hold release state, as illustrated in FIGS. 8A and8B, the first blade 41 and the second blade 42 run in the direction toopen the apertures 1 a and 2 a, and thereafter the first blade 41 andthe second blade 42 collide with the blade cushioning member 4 while thefirst blade 41 and the second blade 42 overlap each other. The bladecushioning member 4 alleviates the shock applied to the first blade 41and the second blade 42 when the first blade 41 and the second blade 42have been moved.

The periphery of the blade cushioning member 4 is covered with the bladecontact member 5. More specifically, when the first blade 41 and thesecond blade 42 collide with the blade cushioning member 4 while thefirst blade 41 and the second blade 42 overlap each other, the bladecontact member 5 is located between the blade cushioning member 4 andthe blade group including the first blade 41 and the second blade 42.The blade contact member 5 is made of a material having higher degree ofresistance to abrasion than the blade cushioning member 4.

When the first blade 41 and the second blade 42 collide with the bladecushioning member 4, the first blade 41 and the second blade 42 directlycome into contact with the blade contact member 5 without directlycoming into contact with the blade cushioning member 4. Since the bladecontact member 5 is made of a material having high degree of resistanceto abrasion such as metal, it is less likely to generate abrasion powdereven if the first blade 41 and the second blade 42 directly come intocontact with the blade contact member 5. Since the first blade 41 andthe second blade 42 do not come into direct contact with the bladecushioning member 4, the blade cushioning member 4 may be made of amaterial having high cushioning performance even if the material islikely to generate abrasion powder.

As illustrated in FIGS. 8A and 8B, when the first blade 41 and thesecond blade 42 come into contact with the blade contact member 5, thereis a clearance between the protruding portion 11 e of the drive lever 11and the protruding portion 15 b of the blade lever 15 as illustrated inFIG. 8C. In this state, as illustrated in FIG. 7C, the drive lever 11over-charges the blade drive spring 14.

In this state, even when the first blade 41 and the second blade 42 arecaused to run in the opening direction according to the urging forceapplied by the blade return spring 46, the blade lever 15 does not comeinto contact with the drive lever 11. Therefore, the drive lever 11 doesnot receive the shock that is caused when the first blade 41 and thesecond blade 42 are caused to run in the opening direction according tothe urging force applied by the blade return spring 46. When the bladedrive spring 14 is over-charged, the drive lever 11 presses the armature12 onto the yoke 33. When a shock is applied to the drive lever 11 atthis occasion, the attracting surfaces of the armature 12 and the yoke33 are damaged. The damaged attracting surfaces of the armature 12 andthe yoke 33 result in a decrease in the accuracy of exposure, but in thepresent exemplary embodiment, the attracting surfaces of the armature 12and the yoke 33 are not damaged.

When the first blade 41 and the second blade 42 are caused to run in theopening direction according to the urging force applied by the bladereturn spring 46, and the first blade 41 and the second blade 42 comeinto contact with the blade contact member 5, the first blade 41 and thesecond blade 42 bound as illustrated in FIG. 6.

When the shutter unit 100 changes from the pre-release waiting state tothe blade lever hold release state, the second cam gear 22 also rotatesas the first cam gear 21 rotates. The second cam gear 22 is asillustrated in FIG. 8A. That is, the cam follower 36 a of the mirrorlever 36 is in contact with the cam top portion 22 e of the first cam 22a of the second cam gear 22. Therefore, like the state as illustrated inFIG. 7A, the mirror lever 36 is held to charge the mirror lever drivespring 39.

Like the state as illustrated in FIG. 7A, the main mirror 6 is alsourged in a downward direction by the main mirror drive spring 7, and themain mirror 6 comes into contact with the stopper, not illustrated, andthe main mirror 6 is at the lower position. That is, the first blade 41and the second blade 42 open the apertures 1 a and 2 a, but the mainmirror 6 is still at the lower position.

When the motor 47 is continuously energized, the motor 47 rotates thefirst cam gear 21 and the second cam gear 22, so that a mirror leverhold release state C as illustrated in FIG. 6 is attained.

The state C as illustrated in FIG. 6 is the mirror lever hold releasestate. The first cam gear 21 and the second cam gear 22 further rotatefrom the state as illustrated in FIG. 6. As the second cam gear 22rotates, the cam follower 36 a of the mirror lever 36 is no longer incontact with the first cam 22 a of the second cam gear 22. When thefirst cam 22 a moves out of the track along which the cam follower 36 arotates, the charged mirror lever drive spring 39 is released, and themirror lever 36 rotates in the clockwise direction in FIG. 8A by theurging force applied by the mirror lever drive spring 39.

In the pre-release waiting state, there is a clearance between the shaftportion 6 a of the main mirror 6 and the contact portion 36 b of themirror lever 36. Therefore, the mirror lever 36 rotates in the clockwisedirection in FIG. 8A for the distance equivalent to this clearance, andthereafter, the contact portion 36 b of the mirror lever 36 comes intocontact with the shaft portion 6 a of the main mirror 6. When thecontact portion 36 b of the mirror lever 36 comes into contact with theshaft portion 6 a of the main mirror 6, the state D as illustrated inFIG. 6 changes to a mirror lever contact state.

The state as illustrated in FIG. 6 is the mirror lever contact state. Inthis state, the contact portion 36 b of the mirror lever 36 comes intocontact with the shaft portion 6 a of the main mirror 6, and the mirrorlever 36 starts rotating the main mirror 6 in the upward directionagainst the urging force applied by the main mirror drive spring 7.

When the main mirror 6 comes into contact with the stopper, notillustrated, the main mirror 6 bounds as illustrated in FIG. 6, andthereafter the main mirror 6 stops at the upper position. The mirrorlever drive spring 39 has a relatively strong spring force to reduce thetime the main mirror 6 bounds (bounding time). Therefore, this boundingtime is less than a bounding time the first blade 41 and the secondblade 42 bound in the blade lever hold release state. When the boundingof the main mirror 6 converges, a mirror up live view state E asillustrated in FIG. 6 is attained.

The state E as illustrated in FIG. 6 is the mirror up live view state.FIGS. 9A and 9B illustrate a state of the shutter unit 100 in the mirrorup live view state. FIG. 9A is a diagram illustrating the shutter unit100 as viewed from the main mirror 6. FIG. 9B is a diagram illustratingthe shutter unit 100 as viewed from the image sensor 116. It should benoted that the shutter base plate 1, the cover plate 2, and theauxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

In the mirror up live view state, the first cam gear 21 and the secondcam gear 22 stop at positions as illustrated in FIGS. 9A and 9B.

The drive lever 11 and the blade lever 15 are in the same state as thoseillustrated in FIGS. 8A and 8B. That is, the first blade 41 and thesecond blade 42 open the apertures 1 a and 2 a, so that the first blade41 and the second blade 42 are in contact with the blade contact member5. In the mirror up live view state, the roller 13 held on the drivelever 11 is also in contact with the cam top portion 22 d of the secondcam 22 c of the second cam gear 22, and therefore, the blade drivespring 14 is over-charged. Therefore, in the mirror up live view state,there is also a clearance between the protruding portion 11 e of thedrive lever 11 and the protruding portion 15 b of the blade lever 15 asillustrated in FIG. 8C.

As described above, the cam follower 36 a of the mirror lever 36 is nolonger in contact with the first cam 22 a of the second cam gear 22, andthe mirror lever 36 rotates according to the urging force applied by themirror lever drive spring 39. Then, the mirror lever 36 rotates the mainmirror 6 in the upward direction against the urging force applied by themain mirror drive spring 7.

When the motor 47 is stopped in this state, a light flux having passedthrough the interchangeable lens 201 reaches the image sensor 116, andan object image taken by the image sensor 116 is displayed on a displaymonitor, i.e., the imaging apparatus attains a so-called live viewstate.

In the mirror up live view state, the roller 13 held on the drive lever11 is in contact with the cam top portion 22 d of the second cam 22 c ofthe second cam gear 22. Accordingly, even if the coil 34 isde-energized, the first blade 41 and the second blade 42 maintain theapertures 1 a and 2 a open.

In the mirror up live view state, the motor 47 is energized, whichcauses the first cam gear 21 and the second cam gear 22 to rotate, andthe motor 47 is stopped in a set release state F as illustrated in FIG.6.

The state F as illustrated in FIG. 6 is the set release state. FIGS. 10Ato 10D illustrate a state of the shutter unit 100 in the set releasestate. FIG. 10A is a diagram illustrating the shutter unit 100 as viewedfrom the main mirror 6. FIG. 10B is a diagram illustrating the shutterunit 100 as viewed from the image sensor 116. It should be noted thatthe shutter base plate 1, the cover plate 2, and the auxiliary baseplate 31 are omitted to explain operation of each cam gear and eachlever.

In the set release state, the first cam gear 21 and the second cam gear22 stop at positions as illustrated in FIGS. 10A and 10B.

In the set release state, the second cam gear 22 rotates, so that theroller 13 held on the drive lever 11 is no longer in contact with thecam top portion 22 d of the second cam 22 c of the second cam gear 22.As a result, the drive lever 11 rotates in the clockwise direction inFIG. 10A by the urging force applied by the blade drive spring 14, andthe over-charged state of the blade drive spring 14 is released. Evenwhen the roller 13 is no longer in contact with the cam top portion 22 dof the second cam 22 c, the coil 34 is still energized, the armature 12is attracted by the yoke 33, and the first blade 41 and the second blade42 maintain the apertures 1 a and 2 a open.

When the over-charged state of the blade drive spring 14 is released,the flange unit 12 b of the armature 12 comes into contact with theprotrusion unit 11 c of the blade drive member according to the urgingforce applied by the armature spring 17. As a result, as illustrated inFIG. 10C, the drive lever 11 slightly rotates, and the protrudingportion 11 e of the drive lever 11 comes into contact with theprotruding portion 15 b of the blade lever 15. Then, as illustrated inFIG. 10D, the protruding portion 11 e of the drive lever 11 presses theprotruding portion 15 b of the blade lever 15, so that the first blade41 and the second blade 42 are no longer in contact with the bladecontact member 5.

In other words, the coil 34 is energized when the blade drive spring 14is over-charged, so that the yoke 33 attracts the armature 12, andbefore the over-charged state of the blade drive spring 14 is released,the blade lever 15 comes into contact with the drive lever 11.

In the set release state, the main mirror 6 stops at the upper position,like the mirror up live view state.

As illustrated in FIG. 6, reset scanning of pixels of the image sensor116 is performed (hereinafter referred to as electronic first curtaintravel) in the set release state, whereby a photographic exposureoperation starts. A time from when a release signal is input to when theelectronic first curtain travel is performed is a release time lag. Inthe present exemplary embodiment, the opening operation of the firstblade 41 and the second blade 42 of which bounding time is relativelylong is started before the upward moving operation of the main mirror 6of which bounding time is relatively short. If the opening operation ofthe first blade 41 and the second blade 42 and the upward movingoperation of the main mirror 6 are started at the same time, theelectronic first curtain travel cannot be performed unless the boundingof the first blade 41 and the second blade 42 converges even after thebounding of the main mirror 6 converges. Therefore, it takes a longerrelease time lag. In the present exemplary embodiment, in view of thisissue, the upward moving operation of the main mirror 6 is started afterthe opening operation of the first blade 41 and the second blade 42 isstarted.

The upward moving operation of the main mirror 6 is started after theopening operation of the first blade 41 and the second blade 42 isstarted, and this reduces the chance of direct sunlight incident uponthe first blade 41 and the second blade 42. Therefore, even when thefirst blade 41 and the second blade 42 are made of polyethyleneterephthalate including blackening, the first blade 41 and the secondblade 42 are less likely to be damaged by the direct sunlight incidentthereon.

After a time interval corresponding to a set shutter time in secondspasses since the electronic first curtain travel starts, the coil 34 isde-energized, so that a blade running state G as illustrated in FIG. 6is attained.

The state G as illustrated in FIG. 6 is the blade running state. FIGS.11A and 11B illustrate a state of the shutter unit 100 in the bladerunning state. FIG. 11A is a diagram illustrating the shutter unit 100as viewed from the main mirror. FIG. 11B is a diagram illustrating theshutter unit 100 as viewed from the image sensor 116. It should be notedthat the shutter base plate 1, the cover plate 2, and the auxiliary baseplate 31 are omitted to explain operation of each cam gear and eachlever.

As illustrated in FIGS. 11A and 11B, the coil 34 is de-energized, and asa result, the first blade 41 and the second blade 42 cannot maintain theapertures 1 a and 2 a open.

The drive lever 11 rotates as illustrated in FIGS. 11A and 11B accordingto the urging force applied by the blade drive spring 14. When the drivelever 11 rotates, the protruding portion 11 e of the drive lever 11pushes the protruding portion 15 b of the blade lever 15, which causesthe blade lever 15 to rotate. Since the drive lever 11 and the bladelever 15 rotate together, the first blade 41 and the second blade 42 runin a direction to close the apertures 1 a and 2 a against the urgingforce applied by the blade return spring 46

In the set release state as illustrated in FIG. 10, the protrudingportion 11 e of the drive lever 11 is already in contact with theprotruding portion 15 b of the blade lever 15. When the coil 34 isde-energized, the drive lever 11 and the blade lever 15 rotate togetheraccording to the urging force applied by the blade drive spring 14. Inother words, in the present exemplary embodiment, when the first blade41 and the second blade 42 run in the direction to close the apertures 1a and 2 a, the drive lever 11 and the blade lever 15 rotate together inan integrated manner since the first blade 41 and the second blade 42start to run.

There may be a case where the protruding portion 11 e of the drive lever11 collides with the protruding portion 15 b of the blade lever 15 whilethe first blade 41 and the second blade 42 run in the direction to closethe apertures 1 a and 2 a, and thereafter the drive lever 11 and theblade lever 15 rotate together in an integrated manner. In this case,however, the rotating speed changes before and after the collision ofthe drive lever 11 and the blade lever 15, and this reduces theprecision in the running operation of the first blade 41 and the secondblade 42.

In the present exemplary embodiment, before the first blade 41 and thesecond blade 42 run, the drive lever 11 and the blade lever 15 areintegrated, and the drive lever 11 and the blade lever 15 rotatetogether in the integrated manner while the first blade 41 and thesecond blade 42 run. This stabilizes the rotating speed of the drivelever 11 and the blade lever 15, and improves the precision in therunning operation of the first blade 41 and the second blade 42.

Further, since the drive lever 11 and the blade lever 15 rotatetogether, the relative position does not change between the roller 13attached to the roller hold shaft 11 d of the drive lever 11 and theroller receiving portion 15 d of the blade lever 15. Therefore, whilethe first blade 41 and the second blade 42 run in the direction to closethe apertures 1 a and 2 a, no abrasion occurs between the roller 13 andthe roller receiving portion 15 d. Even when the direction of gravityacting on the roller changes due to change of the posture while thefirst blade 41 and the second blade 42 run, the relative position doesnot change between the roller 13 and the roller receiving portion 15 d,and therefore, the abrasion coefficient does not change. In the presentexemplary embodiment, the abrasion is reduced when the first blade 41and the second blade 42 run in the direction to close the apertures 1 aand 2 a, and this improves the precision in the running operation of thefirst blade 41 and the second blade 42.

When the first blade 41 and the second blade 42 run to a position atwhich the apertures 1 a and 2 a are closed, a blade running completionstate H as illustrated in FIG. 6 is attained.

The state H as illustrated in FIG. 6 is the blade running completionstate. FIGS. 12A and 12B illustrate a state of the shutter unit 100 inthe blade running completion state. FIG. 12A is a diagram illustratingthe shutter unit 100 as viewed from the main mirror 6. FIG. 12B is adiagram illustrating the shutter unit 100 as viewed from the imagesensor 116. It should be noted that the shutter base plate 1, the coverplate 2, and the auxiliary base plate 31 are omitted to explainoperation of each cam gear and each lever.

When the engaging portion 15 a formed on the blade lever 15 collideswith the cushioning member 3 provided at the upper portion of thearc-shaped hole 1 e formed in the shutter base plate 1, the first blade41 and the second blade 42 stop at the position at which the apertures 1a and 2 a are closed.

At this occasion, the protruding portion 11 e of the drive lever 11 isin contact with the protruding portion 15 b of the blade lever 15. Inother words, in the present exemplary embodiment, when the first blade41 and the second blade 42 run in the direction to close the apertures 1a and 2 a, the drive lever 11 and the blade lever 15 rotate togetherthroughout the run from the start to the end.

In the blade running completion state as illustrated in FIG. 12, thefirst blade 41 and the second blade 42 close the apertures 1 a and 2 a,so that the blade return spring 46 is charged.

In the blade running completion state, the photo-sensor 32 provided onthe auxiliary base plate 31 is used to detect the blade lever 15 at ablade running completion rotational position.

After a predetermined period of time passes since the coil 34 isde-energized, the motor 47 is energized. When the motor 47 is energized,and the first cam gear 21 and the second cam gear 22 rotate, a mirrorlever charge and cam gear control spring charge release start state I asillustrated in FIG. 6 is attained.

The state I as illustrated in FIG. 6 is the mirror lever charge and camgear control spring charge release start state. FIGS. 13A and 13Billustrate a state of the shutter unit 100 in the mirror lever chargeand cam gear control spring charge release start state. FIG. 13A is adiagram illustrating the shutter unit 100 as viewed from the main mirror6. FIG. 13B is a diagram illustrating the shutter unit 100 as viewedfrom the image sensor 116. It should be noted that the shutter baseplate 1, the cover plate 2, and the auxiliary base plate 31 are omittedto explain operation of each cam gear and each lever.

The first cam gear 21 and the second cam gear 22 rotate from the stateas illustrated in FIGS. 12A and 12B, the first cam 22 a of the secondcam gear 22 comes into contact with the cam follower 36 a of the mirrorlever 36. At the same time or slightly after this, the third cam 22 d ofthe second cam gear 22 starts to release charging of the cam gearcontrol spring 50.

When the second cam gear 22 rotates, the first cam 22 a of the secondcam gear 22 pushes the cam follower 36 a of the mirror lever 36.Accordingly, the mirror lever 36 rotates in the counterclockwisedirection in FIG. 13A, and the mirror lever 36 charges the mirror leverdrive spring 39. When the mirror lever 36 rotates in thecounterclockwise direction in FIG. 13A, the main mirror 6 rotates in thedownward direction according to the urging force applied by the mainmirror drive spring 7.

Further, the movable arm portion 50 a of the cam gear control spring 50pushes the third cam 22 d of the second cam gear 22, which urges thesecond cam gear 22 in the counterclockwise direction in FIG. 13B. Inother words, when charging of the cam gear control spring 50 isreleased, the cam gear control spring 50 applies urging force to thesecond cam gear 22. This urging force is in the direction opposite tothe urging force applied by the mirror lever drive spring 39, andtherefore, the urging force pushes and supports the rotation of thesecond cam gear 22 against the urging force applied by the mirror leverdrive spring 39.

In the mirror lever charge and cam gear control spring charge releasestart state, the first blade 41 and the second blade 42 stop at aposition at which the apertures 1 a and 2 a are closed, like the bladerunning completion state.

When the motor 47 is continuously energized in the mirror lever chargeand cam gear control spring charge release start state, the first camgear 21 and the second cam gear 22 further rotate, and a cam gearcontrol spring charge release completion state J as illustrated in FIG.6 is attained.

The state J as illustrated in FIG. 6 is the cam gear control springcharge release completion state. FIGS. 14A and 14B illustrate a state ofthe shutter unit 100 in the cam gear control spring charge releasecompletion state. FIG. 14A is a diagram illustrating the shutter unit100 as viewed from the main mirror 6. FIG. 14B is a diagram illustratingthe shutter unit 100 as viewed from the image sensor 116. It should benoted that the shutter base plate 1, the cover plate 2, and theauxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

The first cam gear 21 and the second cam gear 22 rotate from the stateas illustrated in FIGS. 13A and 13B. As the second cam gear 22 rotates,the first cam 22 a of the second cam gear 22 pushes the cam follower 36a of the mirror lever 36. As a result, the mirror lever 36 rotates inthe counterclockwise direction in FIG. 14A, and the mirror lever drivespring 39 is charged. When the mirror lever 36 rotates in thecounterclockwise direction in FIG. 14A, the main mirror 6 rotates in thedownward direction according to the urging force applied by the mainmirror drive spring 7.

When this state is attained, charging of the cam gear control spring 50is completely released, and the cam gear control spring 50 no longerapplies any urging force to the second cam gear 22. As a result, the camgear control spring 50 no longer pushes and supports the rotation of thesecond cam gear 22.

Further, the motor 47 is energized, so that the first cam gear 21 andthe second cam gear 22 rotate via the reduction gear train 48.

In the present exemplary embodiment, at the same time or slightly afterthe mirror lever drive spring 39 starts charging, charging of the camgear control spring 50 starts to be released, and while the mirror leverdrive spring 39 is charged, charging of the cam gear control spring 50is configured to be completely released. However, the configuration isnot limited thereto. From when the mirror lever drive spring 39 startscharging to when the mirror lever drive spring 39 finishes charging,charging of the cam gear control spring 50 may start to be released, andcharging of the cam gear control spring 50 may be completely released.In this configuration, the drive force of the motor 47 required tocharge the mirror lever drive spring 39 can be reduced.

The state K as illustrated in FIG. 6 is a mirror lever charge completionstate. FIGS. 15A and 15B illustrate a state of the shutter unit 100 inthe mirror lever charge completion state. FIG. 15A is a diagramillustrating the shutter unit 100 as viewed from the main mirror 6. FIG.15B is a diagram illustrating the shutter unit 100 as viewed from theimage sensor 116. It should be noted that the shutter base plate 1, thecover plate 2, and the auxiliary base plate 31 are omitted to explainoperation of each cam gear and each lever.

When the second cam gear 22 further rotates in the counterclockwisedirection in FIG. 15A from the mirror lever charge state, the mirrorlever 36 charges the mirror lever drive spring 39. As the mirror lever36 rotates, the main mirror 6 further rotates in the downward direction,comes into contact with the stopper, not illustrated, and then stops.Even after the main mirror 6 stops at the lower position, the second camgear 22 rotates, and the cam follower 36 a of the mirror lever 36reaches the cam top position 22 e of the first cam 22 a of the secondcam gear 22. At this occasion, as illustrated in FIG. 15A, there is aclearance between the shaft portion 6 a of the main mirror 6 and thecontact portion 36 b of the mirror lever 36. Therefore, even if erroroccurs in the position of the mirror lever 36, the position of the mainmirror 6 is held at the correct position by the stopper, notillustrated.

When the motor 47 is continuously energized in the mirror lever chargecompletion state, the first cam gear 21 and the second cam gear 22further rotate, so that a blade lever holdable state L as illustrated inFIG. 6 is attained.

The state L as illustrated in FIG. 6 is the blade lever holdable state.FIGS. 16A and 16B illustrate a state of the shutter unit 100 in theblade lever holdable state. FIG. 16A is a diagram illustrating theshutter unit 100 as viewed from the main mirror 6. FIG. 16B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

When the first cam gear 21 rotates, the cam 21 b of the first cam gear21 moves to a position at which the cam follower 15 e of the blade lever15 can come into contact. In the blade lever holdable state asillustrated in FIGS. 16A and 16B, the urging force applied by the bladedrive spring 14 causes the protruding portion 11 e of the drive lever 11to push the protruding portion 15 b of the blade lever 15, andtherefore, the cam follower 15 e of the blade lever 15 is not in contactwith the cam 21 b of the first cam gear 21

When the motor 47 is continuously energized in the blade lever holdablestate, the first cam gear 21 and the second cam gear 22 rotate, so thata drive lever charge state M as illustrated in FIG. 6 is attained.

The state M as illustrated in FIG. 6 is the drive lever charge state.FIGS. 17A and 17B illustrate a state of the shutter unit 100 in thedrive lever charge state. FIG. 17A is a diagram illustrating the shutterunit 100 as viewed from the main mirror 6. FIG. 17B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

When the second cam gear 22 rotates, the second cam 22 c of the secondcam gear 22 pushes the roller 13 held on the drive lever 11. As aresult, the drive lever 11 rotates in the counterclockwise direction inFIG. 17A, and charges the drive spring 14. When the drive lever 11rotates in the counterclockwise direction in FIG. 17A, the protrudingportion 11 e of the drive lever 11 and the protruding portion 15 b ofthe blade lever 15 are no longer in contact with each other.Accordingly, the blade lever 15 rotates in the counterclockwisedirection in FIG. 17B according to the urging force applied by the bladereturn spring 46, and the cam follower 15 e of the blade lever 15 comesinto contact with the cam 21 b of the first cam gear 21. As a result,the blade lever 15 is held at the position as illustrated in FIG. 17B,and the first blade 41 and the second blade 42 maintain the apertures 1a and 2 a closed.

When the motor 47 is continuously energized in the drive lever chargestate, the second cam gear 22 further rotates, so that a drive levercharge completion state N as illustrated in FIG. 6 is attained.

The state N as illustrated in FIG. 6 is the drive lever chargecompletion state.

When the roller 13 held on the drive lever 11 reaches the cam topportion 22 d of the second cam 22 c of the second cam gear 22, the drivelever 11 over-charges the blade drive spring 14. In this state, themotor 47 is de-energized.

Even after the motor 47 is de-energized, the second cam gear 22continues to rotate due to inertia until the second cam gear 22completely stops.

Substantially at the same time as de-energizing the motor 47, the thirdcam 22 d of the second cam gear 22 comes into contact with the movablearm portion 50 a of the cam gear control spring 50, and starts chargingthe cam gear control spring 50. When the cam gear control spring 50 ischarged, the rotation of the second cam gear 22 is suppressed by causingthe cam gear control spring 50 to give a side pressure to the third cam22 d. That is, the cam gear control spring 50 brakes the second cam gear22.

As a result, each constituent component including the second cam gear 22completely stops, and the state A as illustrated in FIG. 6 (pre-releasewaiting state) is attained.

The first state is from the state N as illustrated in FIG. 6 to thestate immediately before the state B as illustrated in FIG. 6. In thefirst state, the charge cam member charges the mirror lever drive springand the blade drive spring, so that the hold cam member holds the bladelever. The second state is from the state D as illustrated in FIG. 6 tothe state immediately before the state G as illustrated in FIG. 6. Inthe second state, the charge cam member releases charging of the mirrorlever drive spring, and charges the blade drive spring, so that the holdcam member releases holding of the blade lever. The third state is fromthe state H as illustrated in FIG. 6 to the state immediately before thestate I as illustrated in FIG. 6. In the third state, the charge cammember releases charging of the mirror lever drive spring and chargingof the blade drive spring, so that the hold cam member releases holdingof the blade lever.

A modification of the present exemplary embodiment will be describedwith reference to FIG. 18 to FIGS. 20A and 20B.

FIG. 18 is a timing chart illustrating operation timing of the mirrorlever 36, the main mirror 6, the blade lever 15, the drive lever 11, thecoil 34, the blade group, the image sensor 116, and the cam gear controlspring 50.

The states A to H as illustrated in FIG. 18 are the same as those of theabove exemplary embodiment, and description thereabout is omitted.

A state I1 as illustrated in FIG. 18 is a mirror lever charge state.FIGS. 19A and 19B illustrate a state of the shutter unit 100 in themirror lever charge state. FIG. 19A is a diagram illustrating theshutter unit 100 as viewed from the main mirror 6. FIG. 19B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

When the first cam gear 21 and the second cam gear 22 rotate from thestate as illustrated in FIGS. 12A and 12B, the first cam 22 a of thesecond cam gear 22 comes into contact with the cam follower 36 a of themirror lever 36.

When the second cam gear 22 rotates, the first cam 22 a of the secondcam gear 22 pushes the cam follower 36 a of the mirror lever 36.Accordingly, the mirror lever 36 rotates in the counterclockwisedirection in FIG. 19A, and the mirror lever 36 charges the mirror leverdrive spring 39. When the mirror lever 36 rotates in thecounterclockwise direction in FIG. 19A, the main mirror 6 rotates in thedownward direction according to urging force applied by a main mirrordrive spring 7.

At this occasion, the arm portion 50 a of the cam gear control spring 50comes into contact with the third cam 22 d of the second cam gear 22,and the charging operation of the cam gear control spring 50 iscompleted. This is the only difference from the state I as illustratedin FIG. 6, i.e., the only difference from the mirror lever charge andcam gear control spring charge release start state as illustrated inFIG. 13.

In the mirror lever charge state, the first blade 41 and the secondblade 42 stop at the position at which the apertures 1 a and 2 a areclosed, like the blade running completion state.

When the motor 47 is continuously energized in the mirror lever chargestate, the first cam gear 21 and the second cam gear 22 further rotate,and a mirror lever charge completion state K1 as illustrated in FIG. 18is attained.

The state K1 as illustrated in FIG. 18 is the mirror lever chargecompletion state. FIGS. 20A and 20B illustrate a state of the shutterunit 100 in the mirror lever charge completion state. FIG. 20A is adiagram illustrating the shutter unit 100 as viewed from the main mirror6. FIG. 20B is a diagram illustrating the shutter unit 100 as viewedfrom the image sensor 116. It should be noted that the shutter baseplate 1, the cover plate 2, and the auxiliary base plate 31 are omittedto explain operation of each cam gear and each lever.

When the second cam gear 22 further rotates in the counterclockwisedirection in FIG. 20A from the mirror lever charge state, the mirrorlever 36 charges the mirror lever drive spring 39. As the mirror lever36 rotates, the main mirror 6 further rotates in the downward direction,comes into contact with the stopper, not illustrated, and then stops.Even after the main mirror 6 stops at the lower position, the second camgear 22 rotates, and the cam follower 36 a of the mirror lever 36reaches the cam top position 22 e of the first cam 22 a of the secondcam gear 22. At this occasion, as illustrated in FIG. 20A, there is aclearance between the shaft portion 6 a of the main mirror 6 and thecontact portion 36 b of the mirror lever 36. Therefore, even if erroroccurs in the position of the mirror lever 36, the position of the mainmirror 6 is held at the correct position by the stopper, notillustrated.

At this occasion, the arm portion 50 a of the cam gear control spring 50comes into contact with the third cam 22 d of the second cam gear 22,and the charging operation of the cam gear control spring 50 iscompleted. This is the only difference from the state K as illustratedin FIG. 6, i.e., the only difference from the mirror lever chargecompletion state as illustrated in FIG. 15.

When the motor 47 is continuously energized in the mirror lever chargecompletion state, the first cam gear 21 and the second cam gear 22further rotate, so that a blade lever holdable state L1 as illustratedin FIG. 18 is attained.

The state L1 as illustrated in FIG. 18 is the blade lever holdablestate. FIGS. 21A and 21B illustrate a state of the shutter unit 100 inthe blade lever holdable state. FIG. 21A is a diagram illustrating theshutter unit 100 as viewed from the main mirror 6. FIG. 21B is a diagramillustrating the shutter unit 100 as viewed from the image sensor 116.It should be noted that the shutter base plate 1, the cover plate 2, andthe auxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

When the first cam gear 21 rotates, the cam 21 b of the first cam gear21 moves to a position at which the cam follower 15 e of the blade lever15 can come into contact. In the blade lever holdable state asillustrated in FIGS. 21A and 21B, the urging force applied by the bladedrive spring 14 causes the protruding portion 11 e of the drive lever 11to push the protruding portion 15 b of the blade lever 15, andtherefore, the cam follower 15 e of the blade lever 15 is not in contactwith the cam 21 b of the first cam gear 21

At this occasion, the arm portion 50 a of the cam gear control spring 50comes into contact with the third cam 22 d of the second cam gear 22,and the charging operation of the cam gear control spring 50 iscompleted. This is the only difference from the state L as illustratedin FIG. 6, i.e., the only difference from the blade lever holdable stateas illustrated in FIGS. 16A and 16B.

When the motor 47 is continuously energized in the blade lever holdablestate, the first cam gear 21 and the second cam gear 22 further rotate,and a drive lever charge and cam gear control spring charge releasestart state M1 as illustrated in FIG. 18 is attained.

The state M1 as illustrated in FIG. 18 is the drive lever charge and camgear control spring charge release start state. FIGS. 22A and 22Billustrate a state of the shutter unit 100 in the drive lever charge andcam gear control spring charge release start state. FIG. 22A is adiagram illustrating the shutter unit 100 as viewed from the main mirror6. FIG. 22B is a diagram illustrating the shutter unit 100 as viewedfrom the image sensor 116. It should be noted that the shutter baseplate 1, the cover plate 2, and the auxiliary base plate 31 are omittedto explain operation of each cam gear and each lever.

When the second cam gear 22 rotates, the second cam 22 c of the secondcam gear 22 pushes the roller 13 held on the drive lever 11. As aresult, the drive lever 11 rotates in the counterclockwise direction inFIG. 22A, and charges the drive spring 14. When the drive lever 11rotates in the counterclockwise direction in FIG. 22A, the protrudingportion 11 e of the drive lever 11 and the protruding portion 15 b ofthe blade lever 15 are no longer in contact with each other.Accordingly, the blade lever 15 rotates in the counterclockwisedirection in FIG. 22B according to the urging force applied by the bladereturn spring 46, and the cam follower 15 e of the blade lever 15 comesinto contact with the cam 21 b of the first cam gear 21. As a result,the blade lever 15 is held at the position as illustrated in FIG. 22B,and the first blade 41 and the second blade 42 maintain the apertures 1a and 2 a closed.

When the motor 47 is continuously energized in the drive lever chargestate, the second cam gear 22 further rotates, so that a cam gearcontrol spring charge release completion state M2 as illustrated in FIG.18 is attained.

The state M2 as illustrated in FIG. 18 is the cam gear control springcharge release completion state. FIGS. 23A and 23B illustrate a state ofthe shutter unit 100 in the cam gear control spring charge releasecompletion state. FIG. 23A is a diagram illustrating the shutter unit100 as viewed from the main mirror 6. FIG. 23B is a diagram illustratingthe shutter unit 100 as viewed from the image sensor 116. It should benoted that the shutter base plate 1, the cover plate 2, and theauxiliary base plate 31 are omitted to explain operation of each camgear and each lever.

The first cam gear 21 and the second cam gear 22 further rotate from thestate as illustrated in FIGS. 22A and 22B. As the second cam gear 22rotates, the first cam 22 a of the second cam gear 22 pushes the camfollower 36 a of the mirror lever 36. As a result, the mirror lever 36rotates in the counterclockwise direction in FIG. 23A, and the mirrorlever drive spring 39 is charged. When the mirror lever 36 rotates inthe counterclockwise direction in FIG. 23A, the main mirror 6 rotates inthe downward direction according to the urging force applied by the mainmirror drive spring 7.

When this state is attained, charging of the cam gear control spring 50is completely released, and the cam gear control spring 50 no longerapplies any urging force to the second cam gear 22. As a result, the camgear control spring 50 no longer pushes and supports the rotation of thesecond cam gear 22.

Further, the motor 47 is energized, so that the first cam gear 21 andthe second cam gear 22 rotate with the reduction gear train 48. When thesecond cam gear 22 further rotates, a drive lever charge completionstate N as illustrated in FIG. 18 is attained. The drive lever chargecompletion state N as illustrated in FIG. 18 is the same as the aboveembodiment, and description thereabout is omitted.

In the above modification, the cam gear control spring 50 starts to bereleased while the blade drive spring 14 is charged, and charging of thecam gear control spring 50 is completely released while the blade drivespring 14 is charged. However, the configuration is not limited thereto.From when the blade drive spring 14 starts charging to when the bladedrive spring 14 finishes charging, charging of the cam gear controlspring 50 may start to be released, and charging of the cam gear controlspring 50 may be completely released. In this configuration, the driveforce of the motor 47 required to charge the blade drive spring 14 canbe reduced.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

This application claims priority from Japanese Patent Application No.2010-268752 filed Dec. 1, 2010, which is hereby incorporated byreference herein in its entirety.

1. A shutter device for use in an imaging apparatus including a mirrorthat can move back and forth in a photographic optical path, the shutterdevice comprising: a shutter plate formed with an aperture through whicha photographic light flux passes; a shutter blade configured to closeand open the aperture; a blade lever configured to rotate, thereby beingcoupled with the shutter blade; a blade return spring configured to urgethe blade lever in a direction in which the shutter blade opens theaperture; a drive lever configured to rotate around a rotation shaft ofthe blade lever to drive the blade lever; a blade drive springconfigured to urge the drive lever; a mirror lever configured to drivethe mirror; a mirror lever drive spring configured to urge the mirrorlever; a charge cam member configured to rotate to charge the mirrorlever drive spring and the blade drive spring, the charge cam memberhaving a first cam portion and a second cam portion formed thereon,wherein the first cam portion comes into contact with the mirror lever,and the second cam portion comes into contact with the drive lever; ahold cam member configured to rotate to switch between a state in whichthe blade lever is held so that the shutter blade closes the apertureand a state in which holding of the blade lever is released, wherein thehold cam member has a hold cam portion formed thereon, the hold camportion coming into contact with the blade lever to hold the blade leverso that the shutter blade closes the aperture, wherein the charge cammember and the hold cam member are arranged such that when the chargecam member rotates one turn, the hold cam member also rotates one turn,wherein when the charge cam member and the hold cam member rotate oneturn, the shutter device is arranged to change to a first state, asecond state, and a third state in this order, wherein in the firststate, the charge cam member is arranged to charge the mirror leverdrive spring and the blade drive spring, so that the hold cam memberholds the blade lever, wherein in the second state, the charge cammember is arranged to release charging of the mirror lever drive springand to charge the blade drive spring, so that the hold cam memberreleases holding of the blade lever, and wherein in the third state, thecharge cam member is arranged to release charging of the mirror leverdrive spring and to release charging of the blade drive spring, so thatthe hold cam member releases holding of the blade lever.
 2. The shutterdevice according to claim 1, wherein when the shutter device changesfrom the first state to the second state, the hold cam member isarranged to release holding of the blade lever, and thereafter thecharge cam member is arranged to release charging of the mirror leverdrive spring.
 3. The shutter device according to claim 1, wherein whenthe shutter device changes from the third state to the first state, thecharge cam member is arranged to charge the mirror lever drive spring,and thereafter the hold cam member is arranged to be ready to hold theblade lever, and the charge cam member is arranged to charge the bladedrive spring.
 4. An imaging apparatus comprising: an image sensor; andthe shutter device according to claim 1 configured to adjust an amountof exposure on the image sensor.